Subarachnoid haemorrhage Flashcards
What is a subarachnoid haemorrhage?
This is a haemorrhage underneath the arachnoid mater - between arachnoid mater and pia mater
What is the typical presentation of subarachnoid haemorrhage? 8 features
- acute severe headache - like blow to back of head with baseball bat
- occipital headache
- neck stiffness, photophobia (meningism)
- pain maximal at headache onset
- seizures
- neurological deficits
- decreased consciousness/coma
- death
What are 4 risk factors for haemorrhagic stroke?
- Age
- Hypertension
- Arteriovenous malformation
- Anticoagulation therapy
What are 4 features that may help differentiate haemorrhagic from ischaemic stroke, that are more common in haemorrhagic?
- Decreased level of consciousness (up to 50% of patients)
- Headache
- Nausea and vomiting
- Seizures (in up to 25%)
What is the most common cause of subarachnoid haemorrhage?
head injury - truamatic SAH
What are 2 broad types of subarachnoid haemorrhage?
- Traumatic SAH (most common)
- Spontaneous SAH
What are 6 causes of spontaneous SAH?
- Intracranial aneurysm (saccular ‘berry’ aneurysms)
- Arteriovenous malformation
- Pituitary apoplexy (bleeding into it/impaired blood supply)
- Arterial dissection
- Mycotic (infective) aneurysms
- Perimesencephalic (idiopathic venous bleed)
What is the commonest cause of spontaneous SAH?
intracranial aneurysm - saccular aneurysms (85%)
What are 3 examples of conditions associated with berry aneurysms?
- Adult polycystic kidney disease
- Ehlers Danlos syndrome
- Coarctation of the aorta
What ECG changes may sometimes be seen in sabarachnoid haemorrhage?
ST elevation
What is the first line investigation used to diagnose subarachnoid haemorrhage and what will it show?
CT: acute blood (hyperdense/bright on CT) distributed in basal cisterns, sulci and in severe cases the ventricular system
What are 3 places where hyperdense/bright blood may be seen on CT in SAH?
- Basal cisterns
- Sulci
- Ventricular system (severe cases)
In what proportion of cases of SAH is CT negative?
7%
If CT is negative for SAH what is the next investigation which can confirm if SAH is present?
Lumpar puncture
When must lumbar puncture be performed when being used to help confirm SAH?
at least 12 hours following onset of symptoms to allow development of xanthochromia (result of red blood cell breakdown)
What will be seen on lumbar puncture in SAH? 2 things
- xanthochromia (result of red blood cell breakdown)
- normal or raised opening pressure
Why is xanthochromia used to help diagnosed SAH from LP?
helps distinguish true SAH from a ‘traumatic tap’ (blood introduced by LP procedure)
What is the next step of management as soon as SAH is confirmed?
referral to neurosurgery
After spontaneous SAH is confirmed, what is the aim of investigations following this?
identify causative pathology that needs urgent treatment -
CT intracranial angiogram (to identify vascular lesion e.g. aneurysm or AVM) ± digital subtraction angiogram (catheter angiogram)
What investigations can be used to help identify the underlying cause of spontaneous SAH?
CT intracranial angiogram (to identify vascular lesion e.g. aneurysm or AVM) ± digital subtraction angiogram (catheter angiogram)
What is the treatment of spontaneous SAH based upon?
should be in accordance with causative pathology
Within what time frame do intracranial aneurysms require intervention?
within 24 hours
Why is prompt (in 24h) intervention required for intracranial aneurysms?
they are at risk of rebleeding
How are most intracranial aneurysms treated? What else can be offered?
- with a coil by interventional neuroradiologists
- a minotirty require craniotomy and clipping by neurosurgeon
What is the management of patients with SAH until the aneurysm is treated (by inteventional radiologists/surgeons)?
strict bed rest, well-controlled blood pressure, avoid straining to prevent re-bleed
What drug is given following SAH and why?
Nimodipine 21 day course
To prevent vasospasm and maintain cerebral perfusion
What are 3 aspects to the treatment of vasospasm following SAH if it occurs?
Hypervolaemia, induced-hypertension and haemodilution
How is nimodipine thought to work?
calcium chanenel inhibitor targeting the brain vasculature - thought to prevent vasospasm (but unclear from studies)
How can hydrocephalus induced by SAH be treated? Short- and long-term
- temporarily with external ventricular drain (CSF diverted into bag at the bedside)
- if required long term: ventriculo-peritoneal shunt
What are 6 complications of aneurysmal SAH?
- Re-bleeding
- Vasospasm (delayed cerebral ischaemia)
- Hyponatraemia (usually due to SIADH)
- Seizures
- Hydrocephalus
- Death
In what proportion of cases of SAH does rebleeding occur?
10%
Within what period following SAH is rebleeding most common?
first 12 hours
What investigation should be performed if rebleeding is suspected?
repeat CT
What might make you suspect rebleeding following SAH?
sudden worsening of neurological symptoms
When does vasospasm typically occur following SAH?
7-14 days after onset
What is the most common cause of hyponatraemia following SAH?
SIADH: syndrome of inappropriate anti-diuretic hormone
What are the 3 important predictive factors in SAH?
- Conscious level on admission
- Age
- Amount of blood visible on CT head
Which investigation is considered the gold standard for detection, demonstation and localisation of ruptured aneurysms?
cerebral CT angiography
